Aerosol can

ABSTRACT

The invention relates to a spray dispenser having an elastic filling substance reservoir serving as energy storage chamber; an expansion body that is enclosed tightly by the filling substance reservoir in the unfilled condition and at the same time expands the filling substance reservoir against the elastic force thereof; an inlet for the introduction of filling substance during further expansion of the filling substance reservoir into the interstitial area resulting thereby; and an outlet for delivering the filling substance when spraying.

FIELD OF THE INVENTION

The invention relates to a spray dispenser for delivering a substance from a spray nozzle. The substance may be delivered in the form of a fine mist, but also in form of an atomized stream with larger drops. In all cases, such spray dispensers include a filling substance reservoir which receives the filling substance, and also a valve unit that is connected to the filling substance reservoir, with a spray head which in turn is furnished with a spray nozzle.

BACKGROUND OF THE INVENTION

There are several possibilities for expelling the filling substance from the filling substance reservoir, and these are realized in various spray dispenser constructions. For example, expulsion of the filling substance by means of a gas propellant is known. This principle is the worst, because the gas propellant is known to be highly harmful to the environment. In particular, because the gas propellant has strong dependency on its temperature, the function of the spray system is only possible within a narrowly defined temperature range.

Another possibility is to expel the filling substance from the filling substance reservoir by manual pressure on a displacement piston. However, this principle does not meet the requirement of convenience. According to this method, the spray nozzle should be generally oriented in a certain direction; when hand pressure is applied, the nozzle frequently deviates from this direction.

A further known construction uses a receptacle made from an elastomer material as a filling substance reservoir. This material is capable of expansion. When the filling substance is introduced (“charging”), the reservoir expands. Due to its intrinsic elastic force it exerts a pressure filling substance. When the valve is opened by light pressure on the spray head, the reservoir ejects a quantity of the filling substance through the spray nozzle because of the reservoir's own elastic force indicated above.

This principle has one disadvantage. This is that the elastic force is constantly weakened over the course of time as the filling substance reservoir becomes progressively emptier. This means that the spray pressure and thus also the volume of the spray jet expelled through the spray nozzle diminishes over time. The resulting effort thus changes over the lifetime of a spray dispenser, which is undesirable. Moreover, towards the end of the spray dispenser's lifetime, that is when the spray pressure on the filling substance is very small, a certain quantity remains in the reservoir. This remainder in the reservoir can no longer be expelled because the elastic force has become negligible.

SUMMARY OF THE INVENTION

The object underlying the invention is to design a spray dispenser having a filling substance reservoir made from elastic material such that the elastic force of the reservoir remains at least approximately constant for the majority of the spray dispenser's lifetime, and also particularly in the last phase, that is when only a little filling substance remains in the reservoir, it is still sufficient to be able to expel the last remainder, or at least the majority thereof, from the reservoir. In addition, the residual quantity in the reservoir should be as small as possible and the spray system's should be barely dependent on temperature.

This object is solved by the features of claim 1.

The inventors have taken a new direction. They have introduced an expansion body into the filling substance reservoir, which reservoir is made from elastic material, for example rubber. Thereby, before the two components are assembled, the internal diameter of the reservoir is smaller than the external diameter of the expansion body. The expansion body therefore widens the reservoir during introduction. The reservoir thus tightly encompasses the expansion body and thus places it under a certain tension.

The inventors realized that the stress-strain curve of the elastic material of the filling substance reservoir—with selection of an optimum elastic material-remains at least approximately constant, so that the reservoir's intrinsic elastic force consequently remains unchanged regardless of its expanded condition, and indeed over a relatively large expansion range. This has two advantages: the quality of the spray jet with respect to pressure and volume is largely preserved for the lifetime of the spray dispenser. In addition, towards end of the spray dispenser's life, that is when only a small quantity of filling substance is contained in the reservoir, the material of the reservoir retains sufficient force so that even a residual quantity may be expelled from the reservoir, in large part if not completely.

There are many ways to implement the invention. This begins with the assembly of the expansion body and the filling substance reservoir. The expansion body may be shaped like a projectile and consequently may have a cylindrical form for most of its surface. The contour of the reservoir's inner wall may have the same shape. In any case, the expansion body may be inserted forcefully into the reservoir, with the result that the reservoir is expanded. The effect in this case is to draw the reservoir over the expansion body.

A further possibility consists in expanding the reservoir by means other than with the aid of the expansion body itself. Thus, for example, it is conceivable to introduce multiple rods into the reservoir, which extend parallel to the longitudinal axis of the reservoir and are displaced radially, thereby expanding the reservoir. Thereupon the expansion body may be easily introduced with the reservoir in the expanded condition.

Yet another possibility is to apply a vacuum to the outer surface of the reservoir in order to achieve an expansion, then to introduce the expansion body into the reservoir, and finally to remove the vacuum again.

All spray nozzles of whatever kind must of course have an opening for introduction of the filling substance, and also an opening for its expulsion. The valve indicated in the aforegoing is located in the opening for expulsion. This is opened by pressure on the spray head—generally with the forefinger.

Thereby, the design may be configured such that only one valve is present. This serves both for filling the reservoir and also to release the filling substance for the purpose of spraying. In such a case, the valve is a clack valve, which allows the filling substance—without pressure being exerted on the spray head—to pass through in one direction only, that is the filling direction.

An especially interesting embodiment consists in providing the expansion body with a channel that extends through the expansion body. The channel may pass through the expansion body in the axial direction over its entire length. If the shape of the reservoir is imagined as that of a sack, the channel in the expansion body would open in the area of the bottom of the sack. However, it is also conceivable to provide the channel with lateral outflows, so that several partial channels have their openings on the inner wall of the filling substance reservoir. It is also advantageous to provide channels in the longitudinal direction of the expansion body for purposes of assembling the expansion body, and thus create optimal conditions for the subsequent filling process.

There is a wide range of design possibilities for the individual elements of the spray dispenser according to the invention. A selection of such possibilities is listed in the following:

-   -   The reservoir is constructed from two or more layers. The outer         layer is made from chemically cross-linked elastomer or from         natural rubber or synthetic rubber, or from mixtures of the two.     -   The inner layer may be made from an inert material that does not         react with the filling substance and does not impair the quality         thereof. Here, silicone or silicone rubber for example are         possible materials. One or more layers may also consist of         thermoplastic elastomer (TPE).     -   A barrier layer may also be provided between an inner and an         outer layer, preventing the filling substance or components of         the filling substance from diffusing through the reservoir.     -   The outer layer only has to partially enclose the inner layer or         layers.     -   The partially closed layer may have the form of a cage made from         rings or of longitudinal bracing members or of spirals or mesh.     -   Several expansion bodies may be provided instead of a single         expansion body. These may be combined for form a single         expansion body, which for example has the shape of a projectile.         It is also conceivable to use several expansion bodies having         different external dimensions. Thus the expansion body may be         furnished with ribs that extend circumferentially and prevent         flat contact with the interior surface of the filling substance         reservoir.     -   The expansion body may be equipped with extensions at one or         both ends, for example in the manner of a manifold, with which         the expansion body is retained in the reservoir.

There are several possibilities for ensuring expansion of the reservoir. As indicated in the aforegoing, this may be effected by passing the reservoir forcibly over the expansion body. Pincer-type rods are also possible, which are inserted into the reservoir so as to expand it, and then to allow introduction of the expansion body. In addition, it is possible to introduce the expansion body into the reservoir, wherein the expansion body initially is not larger than the reservoir, but subsequently to increase the dimensions of the expansion body by other means, for example by heating or foam expansion or—if a hollow expansion body is used—by inflating it with a liquid or gaseous medium. Another possibility consists in inserting an expansion body into the reservoir that is not larger than the reservoir and then causing it to swell using components added to or contained in the filling substance, thus causing the dimensions thereof to increase and creating the necessary state of stress.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail with reference to the drawings. The drawings show in detail:

FIG. 1 a diagrammatic lengthwise section of the essential parts of a spray dispenser.

FIG. 2 a second embodiment of a spray dispenser in a view similar to that of FIG. 1.

FIG. 3 illustrates the stress-strain behaviour of the elastic material from which a filling substance reservoir according to the invention is constructed.

DETAILED DESCRIPTION OF THE INVENTION

The spray dispenser shown in FIG. 1 includes a filling substance reservoir 1. In the present case this is double walled. Specifically, it consists of a combination of an external container 1.2 and an internal container 1.1. Internal container 1.1 is made from a material that is inert with respect to the filling substance in question. External container 1.2 is made from an elastic material, which forms the energy storage medium. The two containers are arranged so that their corresponding surfaces are directly adjacent one another. They retain this contact even under any operating state. The internal container thus follows movement of the external container as it expands or contracts.

External container 1.2 is enlarged in its upper area to form a flange 1.2.1. The flange is cylindrical.

A pot-shaped mounting body 2 is also shown. This tightly encloses flange 1.2.1. Mounting body 2 has a cylindrical peripheral wall 2.1, a circular plate 2.2 and a collar 2.3.

Mounting body 2 is itself enclosed by an accommodating hollow body 3, specifically by throat 3.1 thereof. Mounting body 2 is thus secured against axial displacement.

Flange 1.2.1 of external container 1.2 encloses a valve 4. To this is connected a filling and emptying connector 5. Filling substance is introduced through filling and emptying connector 5 and through valve 4 for the purpose of filling, and when the spray dispenser is used, is also ejected therethrough in the opposite direction. This process will be explained in detail below.

The most important element according to the invention is an expansion body 6. This is enclosed by internal container 1.1. It is furnished with a plurality of grooves equally distributed over its perimeter, so that a corresponding number of longitudinal channels 6.1 is formed. Longitudinal channels 6.1 extend practically the entire length of expansion body 6. Thus, a conduit connection is created between valve 4 and the lower area of filling substance reservoir 1.

The external diameter of the filling substance reservoir is larger than the external diameter of the filling substance reservoir in the unassembled condition. This means that when reservoir 1 is mounted—pulled on—over expansion body 6 it is expanded and thus encloses the latter under stress.

For the purpose of filling, the filling substance is introduced under pressure through filling and emptying connector 5 and further through valve 4 into the upper area of reservoir 1. It then flows downwards through channels 6.1 of expansion body 6. Since the filling takes place under pressure, reservoir 1 is expanded so that it is lifted away from expansion body 6. An annular space is thus created over the entire length of the filling substance reservoir, which is filled with the filling substance. During this expansion, the filling pressure of the filling substance operates against the elastic force that is intrinsic to the reservoir. The expansion of reservoir 1 may be continued until the outer surface of external container 1.2 is largely flush against the inner surface 3.1 of the receiving hollow body. Valve 4 may be constructed as a clack valve 4 so that it initially allows only an inflow of the fill substance, but not a backflow. Valve 4 is further constructed in such manner that the check or blocking function of valve 4 may be prevented, for example by pressing a finger on a plunger—not shown here—which may be a component of filling and emptying connector 5.

Mounting body 2 may be moulded or injected onto reservoir 1, or may be placed thereon as a separate part. It may be made from plastic, metal or a combination thereof.

In very general terms, the connection between mounting body 2 of reservoir 1 and the enclosed hollow body 3 may have the form of a snap-locking connection. Thereby, a hook may be conformed on one of these two fixtures, and corresponding recesses or other mating elements may be conformed on the other. Mounting body 2 may also be made from fibre glass reinforced plastic, for example from fibre glass reinforced polyamide or polyester.

Filling substance reservoir 1 may also be produced in different ways. Accordingly, it may have a varying profile over its length. Hollow body 3 for mounting may be made from metal or plastic or any other material, for example even from cardboard.

One interesting variation consists in that mounting body 2 is adhesively affixed to reservoir 1 during injection moulding. Thereby, an insert may also be attached between these components. The insert may contain the valve and be permanently affixed thereto.

The spray dispenser shown in FIG. 2 differs from the one shown in FIG. 1 as follows:

Filling substance reservoir 1 is only single-walled, not double-walled.

An elastomer end plate 7 is provided.

A positive fitting connection is created between elastomer end plate 7 and the bottom end of reservoir 1, because the bottom end of reservoir 1 is furnished with a flange 1.2.2 that cooperates with a corresponding collar 7.1 of end plate 7. As may be seen, the bottom end of reservoir 1 is open in the unassembled condition—unlike the embodiment according to FIG. 1.

The neck of filling substance reservoir 1 has a bulge 1.2.3, which snaps into a corresponding annular groove in mounting hollow body 3. Bulge 1.2.3 and the associated annular groove extend concentrically with the longitudinal axis of the spray dispenser.

In addition, end plate 7 is provided with a ring 7.2 that may lie flush with internal surface 3.1 of hollow body 3, thus performing a further fixing function.

Longitudinal channels 6.1 of expansion body 6 may—as seen in cross-section—be distributed evenly over the perimeter of expansion body 6. However, it is also sufficient to provide a single such longitudinal channel. Also, in addition to or instead of any longitudinal channels 6.1 on the periphery, a central aperture may be provided that penetrates the expansion body 6 for the entire length thereof. In such a case, the filling substance is introduced into the central channel through valve 4 from above during filling, and exits there from at the lower end. During expulsion, in the case of FIG. 1 it is forced against the inner surface of internal container 1.1, and in the case of FIG. 2 against surface 7.4 of end plate 7.

However, it is also possible to provide no longitudinal channels at all, and consequently neither the channels 6.1 shown, which are in the peripheral area of expansion body 6, nor the described central channel. In such a case, the filling substance is again introduced under pressure through filling and emptying connector 5 and through valve 4. It then makes its way between the outer surface of expansion body 6 and the inner surface of reservoir 1, which causes these two surfaces to become separated and reservoir 1 expands until it finally forms a annular space of corresponding thickness and is filled at the same time.

The advantages of the invention are evident upon consideration of the diagram in accordance with FIG. 3. This shows the stress-strain behavior of the material from which reservoir 1 is made—in the case of FIG. 1 of the material of at least one of the container components, i.e. of internal container 1.1 and/or of external container 1.2.

As may be seen from the diagram, there is a range in which the stress-strain behavior is represented by an almost horizontal line.

The corresponding parameters are chosen such that the material of reservoir 1 is already subjected to an initial stress I in the assembled but unfilled condition, and subjected to a final stress II in the filled condition. This means that the spray dispenser—or more precisely the filling substance reservoir 1—operates in the approximately horizontal range indicated. Even if only a small amount of filling substance remains between expansion body 6 and reservoir 1, the material of the reservoir 1 still retains a certain elastic strength, which is sufficient to generate a corresponding spray pressure when the spray dispenser is used. This also serves to ensure that no undesirable residue of the filling substance is left behind in reservoir 1. 

1. A spray dispenser, comprising: 1.1 an elastic filling substance reservoir (1) serving as energy storage medium; 1.2 an expansion body (6) that is enclosed tightly by the filling substance reservoir (1) in the unfilled condition and which expands the filling substance reservoir (1) against the elastic force thereof; 1.3 an inlet for the introduction of filling substance with further expansion of the filling substance reservoir (1) into the resulting interstitial space; and 1.4 an outlet for delivering the filling substance when spraying; and
 2. The spray dispenser according to claim 1, characterized in that the filling substance reservoir (1) is at least double-walled in at least the area contacted by the filling substance.
 3. The spray dispenser according to claim 2, characterized in that the filling substance reservoir (1) is constructed from at least one inner container and an external container (1.1, 1.2), and that at least one of these containers is made from an elastic material.
 4. The spray dispenser according to one of claims 1 to 3, characterized in that recesses are incorporated into the material of the expansion body (6) and/or of the filling substance reservoir (1) to form of longitudinal channels between the expansion body (6) and the filling substance reservoir (1).
 5. The spray dispenser according to one of claims 1 to 4, characterized in that the expansion body is provided with at least one channel in a central area of its cross-section, which extends for a large portion of the length of the expansion body (6), and creates a conduit connection between the inlet for introducing the filling substance and the boundary surface between the expansion body (6) and the inner surface of the filling substance reservoir (1).
 6. The spray dispenser according to one of claims 1 to 5, characterized in that the filling substance reservoir (1) has an annular flange (1.2.1) at its open end, which is conformed or placed or injected thereonto, and which serves to secure the filling substance reservoir (1) lies to a receiving hollow body (3).
 7. The spray dispenser according to claim 6, characterized in that the annular flange is enclosed by a mounting body (2) that is constructed from plastic or metal or from a combination of these two materials.
 8. The spray dispenser according to claim 6 or 7, characterized in that the connection between the mounting body (2) and the hollow body (3) on which it is mounted is realized as snap-locking connection.
 9. The spray dispenser according to claim 8, characterized in that the snap-locking includes hooks or protrusions (2.3).
 10. The spray dispenser according to one of claims 1 to 9, characterized in that in order to create a snap-lock between the upper area of the filling substance reservoir (1) and the hollow receiving body (3), at least a bulge (1.2.3) is provided in one of these two elements, and a corresponding recess is provided in the other of these two elements.
 11. The spray dispenser according to one of claims 6 to 10, characterized in that the mounting body (1.2.1) is made from fiberglass-reinforced polyamide or polyester.
 13. The spray dispenser according to claim 12, wherein said elastic reservoir is double walled at least in the area contacted by the filling substance.
 14. The spray dispenser according to claim 13, wherein said elastic reservoir comprises an inner container and an external container, at least one of said inner and external containers comprising an elastic material.
 15. The spray dispenser according to claim 12, wherein at least one of said expansion body and said inner surface of said elastic reservoir has at least one recess therein, said recess creating at least one channel between said expansion body and said inner surface of said elastic reservoir.
 16. The spray dispenser according to claim 12, wherein said expansion body has at least one axial channel therein, said channel creating a conduit connection between said inlet and a location between said expansion body and said inner surface of said elastic reservoir.
 17. The spray dispenser according to claim 16, wherein said expansion body further comprises lateral outflows extending from said at least one axial channel.
 18. The spray dispenser according to claim 12, wherein said elastic reservoir further comprises an annular flange at said open end, said annular flange sized to engage a hollow receiving body.
 19. The spray dispenser according to claim 18, wherein said annular flange is molded onto said elastic reservoir.
 20. The spray dispenser according to claim 18, wherein said annular flange is enclosed by a mounting body and said mounting body engages said hollow receiving body.
 21. The spray dispenser of claim 20, wherein said mounting body is fabricated from metal, plastic or a combination thereof.
 22. The spray dispenser according to claim 18, wherein said annular flange engages said hollow receiving body as a snap locking connection.
 23. The spray dispenser according to claim 20, wherein said mounting body engages said hollow receiving body as a snap locking connection.
 24. The spray dispenser according to claim 23, wherein said snap locking connection comprises hooks or protrusions.
 25. The spray dispenser according to claim 22, wherein said snap locking connection is formed by a bulge on said annular flange and a corresponding annular groove on said hollow receiving body.
 26. The spray dispenser according to claim 22, wherein said snap locking connection is formed by an annular groove on said annular flange and a corresponding bulge on said hollow receiving body.
 27. The spray dispenser according to claim 20, wherein said mounting body is fabricated from fiber-reinforced polyamide or polyester.
 28. The spray dispenser according to claim 12, wherein said valve is a clack valve. 